Why a Curriculum?
Most music learners have come across T / SD / D (Tonic, Subdominant, Dominant) at some point. Yet very few can listen to a song and instantly say "this is SD, this is D." The reason is simple: knowing the labels and being able to hear them are two completely different skills.
This article is not a conceptual overview of functional harmony — it is a curriculum for actually building the ear. Required background is minimal: working through Lv1 to Lv4 in order takes you to reading 4-bar progressions by function.
The conceptual side (what T / SD / D are and why they are classified that way) is covered in What Is Progression Training?. This article is the practical follow-up.
Design Principle: Two Layers of Labels
Leading with "T / SD / D" alone causes most learners to drop out. The labels carry no meaning yet. Answering "Dominant" without knowing what it feels like is just symbol manipulation — you either guess right or wrong, with no learning underneath.
This curriculum therefore pairs felt labels (stable / opening / wanting to return) with function labels (T / SD / D) at every step. You start with felt labels only, and switch to function labels once recognition is stable.
| Function | Felt label | Chords (Key of C) |
|---|---|---|
| T | Stable / "I'm home" | C, Am, Em |
| SD | Opening / stepping outside | F, Dm |
| D | Wanting to return / pulled back | G, G7 |
The mapping is fixed, so the theory label later snaps into place naturally: "ah, that 'wanting to return' feeling was the Dominant." Going the other way around — theory first — usually doesn't stick.
Why 4 Bars Is the Right Unit
The point of learning to hear function is, ultimately, to follow the flow of real music by ear. So the practice unit should resemble real songs as closely as possible.
Three reasons to choose 4 bars:
- The T → SD → D → T cycle fits naturally. One function per bar across 4 bars = 16 beats. Long enough to develop, short enough to hold in memory.
- Same unit as pop progressions. Standards like I-V-vi-IV, I-IV-V-I, and ii-V-I-I are 4-bar (or 4-chord) units. Practice maps directly to real songs.
- The minimum unit that "feels like music". Single chords or 2-chord pairs feel like drills; 4 bars suddenly sound like a fragment of a song. That feeling sustains motivation.
The 4-Stage Plan
Jumping straight to 4-bar progressions is inefficient. Build the felt sense one at a time. Move to the next level when each Lv's goal is met — there is no fixed schedule.
"Resolved? Or still going?" — Build the D → T feel
Goal: Tell "resolved" from "still going" at 8/10 accuracy.
Play just two chords. The listener answers a simple binary: "did the last chord feel like an ending?" The words "Dominant" and "Tonic" are not used at this stage.
Mix the two patterns equally. Internally these are D → T and T → D, but the labels can wait until the next level. Skip this level and every later answer becomes symbol manipulation.
"Stable" vs "Wanting to Return" — T vs D
Goal: Hear one chord right after the tonic and tell T (stable) from D (wanting to return) at 8/10 accuracy.
The crucial rule: never present chords in isolation. Playing a G on its own and asking "is this D?" is meaningless — G is T or D depending on context. Always anchor with the tonic first, then the test chord: C → G.
In the key of C, use: C = T, G = D, G7 = D. Treat G and G7 as the same function — the learner registers functional sameness over tonal difference.
The answer UI can be either "stable / wanting to return" or "T / D" — pick whichever fits the learner's current state.
Add "Opening" — Introduce SD
Goal: Pick from "stable / opening / wanting to return" for one chord after the tonic at 8/10 accuracy.
SD lacks the clear identity of D. So it is most efficient to teach it by contrast with D: not "wanting to return" — instead "stepping outside" or "opening up."
SD chords in C: F = SD, Dm = SD. Add these to Lv2's C / G / G7 to make the choice a 3-way.
F and Dm sound different but share the SD function. What you are tracking is function, not color. Beginners often get distracted by "F is bright, Dm is dark" — at this level, that distinction is noise.
4-Bar Progression Labeling — The Real Goal
Goal: Hear a 4-bar progression once and label every bar's function (T / SD / D).
Format is simple: listen to a 4-bar progression, then label each bar with one of the three functions.
Beginner (T and D only)
Intermediate (with substitutes)
Advanced (non-standard ordering)
Secondary dominants (V/V, etc.) and borrowed chords are out of scope at Lv4. For instance, the E7 in "| C | E7 | Am | G |" is a secondary dominant — including it now breaks the clean 3-function choice. Stay strictly diatonic in the MVP.
Question Spec
To keep the listener focused on function and nothing else, the audio spec is intentionally simple and fixed.
| Parameter | Recommended |
|---|---|
| Tempo | BPM 70–90 |
| Time signature | 4/4 |
| Per bar | 1 chord |
| Voicing pattern | Block chords (whole notes) |
| Sound | Piano |
| Tonic preview | ON for Lv1–Lv3; toggle at Lv4 |
Arpeggios or rhythmic accompaniments (brushed, bossa, shuffle, etc.) sound richer but pull attention away from function and onto rhythm, color, and texture. Lock voicing to plain block piano chords first; expand timbre only once function recognition is stable.
Designing the Answer UI in Two Layers
For the same correct answer, offer two presentation modes. Learners choose the one that matches their current level.
| Mode | Choice labels | Recommended for |
|---|---|---|
| Beginner mode | stable / opening / wanting to return | Lv1–Lv3 |
| Theory mode | T / SD / D | Lv4 late stage onwards |
| Dual mode | stable (T) / opening (SD) / wanting to return (D) | transitional stage |
Switching to theory mode is never forced. The essential learning is reaching the point where you can answer by feel — labels are a byproduct. That said, talking to other musicians requires the labels, so encourage the move deliberately.
Beyond the Curriculum
Once Lv4 is stable, the next themes layer in. A suggested order:
- Substitute chord recognition — distinguish vi / iii / ii from I / V / IV at the function level.
- Change keys — verify the same skill in keys other than C.
- Take on song-style progressions — identify standards like I-V-vi-IV, ii-V-I, and turnaround patterns by ear.
- Secondary dominants & borrowed chords — sounds that step outside the three-function frame. From here, separate articles take over.
Doing This in Solfege PRO
Solfege PRO's Progression Training can reproduce Lv2 onwards. Mapping between curriculum and app settings:
| Lv | App settings |
|---|---|
| Lv 1 | 2-chord length + Function mode + tonic preview ON. Ideally reskin the answer chips to "stable / wanting to return." |
| Lv 2 | 2-chord length + Function mode + tonic preview ON. Two-way T / D choice. |
| Lv 3 | 2-chord length + Function mode + tonic preview ON. Three-way T / SD / D choice. |
| Lv 4 | 4-chord length + Function mode. Tonic preview ON early, OFF later. |
What Solfege PRO Alone Cannot Cover
Let's be honest.
Lv1 binary (resolved / still going) — the standard answer UI uses T / SD / D labels. For Lv1's binary, you mentally translate "resolved" = T and "still going" = D while practicing.
Automatic felt-label mode — there is no built-in toggle that swaps the function chips for felt labels. Use the mapping table in this article and translate as you go.
Secondary dominants & modulation — this curriculum stays fully diatonic. They matter later but lie outside the app's current scope.
Try Lv1 for 5 minutes and check your baseline
View on App StoreRecommended Path
- Try Lv1 for one session — establish your baseline. Can you tell "resolved" from "still going" instantly? Five minutes is enough.
- 10–15 min/day, 5 days/week — short, frequent. Spacing is the learning.
- Don't advance until you score 8/10 — stay on each level until its goal is met. Skipping ahead breaks Lv4 every time.
- Lv4: tonic preview ON early, OFF late — once OFF works, this skill maps directly to transcribing real songs.
- Verify with songs you love — write out the function labels for a 4-bar chorus you already know. If you can, the curriculum is done.
The right mindset is "move on when the goal is met," not "move on when I understand everything." Perfectionism is the single biggest reason people quit. 8/10 is enough.